The Mycoplasma studies will continue to be concerned with: (I) Energy metabolism of Mycoplasma pneumoniae and its possible relationship to the pathogenicity of the organism with emphasis on the pathways of carbohydrate utilization, H202 production and peroxidase-like activity. (II) Studies with cell-free extracts (CFE) to enlarge on the experimental findings with whole cells especially enzyme determinations (using manometric methods and photometric assays). Presently M. pneumoniae's NADH oxidase activity and H202 formation are being compared to other mycoplasmas. (III) Experimental pathology of M. pneumoniae using guinea pigs, hamsters, and trachea organ cultures. (IV) Comparative microbial physiology of M. pneumoniae with Group D Streptococci, Streptococcus MG and their respective L-forms. The knowledge as well as the methodology gained from the carbohydrate metabolic studies of M. pneumoniae (Objective I) are the starting points of comparison of properties of taxonomic importance found in bacterial parents and their L forms. Hopefully these findings would be useful in understanding M. pneumoniae's relationship to other microorganisms. (V) Cell membrane alteration by M. pneumoniae infection of susceptible tissue cultures and/or trachea organ cultures with reference to "autoimmunity". (VI) Cellular responses of the host in M. pneumoniae infections: mycoplasmacidal activities of whole cell and subcellular fractions particularly of polymorphonuclear leukocytes and alveolar macrophages. (VII) Services: Isolation of classical and T strain mycoplasmas and instruction in mycoplasma techniques. (VIII) Antibiotic resistance in M. pneumoniae with special reference to rifampin and related compounds.